In many applications it is necessary to remove a liquid in vapor form from a gas. This is particularly true where the vapor is water vapor and the gas is compressed air. It has been customary to remove water vapor from compressed air by chilling the air to condense the water vapor therein and then passing the chilled air through a demister section to remove entrained particles of water. For the most part, such systems comprise a series of separate vessels forming the various chambers in which the refrigeration and demisting occurred, and such apparatus was generally designed on an individual basis for the particular installation involved.